How to output (to a log) a multi-level array in a format that is human-readable?

There are a few different ways you can output a multi-level array in a human-readable format, depending on what you mean by "human-readable" and what you want to achieve. Here are a few options:

1. You can use print_r() function in PHP to output the contents of an array in a way that is easy for humans to read. This function will output the array in a nested, tree-like structure, with each level of the array indented to show its hierarchy.

2. If you want to output the array to a log file, you could use var_export() function in PHP, which will output the array as a string of PHP code that can be easily pasted back into a PHP script. This is useful if you want to save the array for later use or analysis.

3. Another option is to use json_encode() function in PHP to convert the array into a JSON string, which can be easily read and understood by humans. JSON is a popular data interchange format that is used to transmit data between a server and a web application, and it is easy for humans to read and understand.

4. If you want to output the array to the command line, you could use var_dump() function in PHP, which will output the contents of the array in a format that is easy for humans to read. This function will output the type and value of each element in the array, as well as its memory location.

I hope this helps! Let me know if you have any questions.